81 research outputs found
Detecting volcanic sulfur dioxide plumes in the Northern Hemisphere using the Brewer spectrophotometer, other networks, and satellite observations
This paper demonstrates that SO 2 columnar amounts have significantly increased following the five
largest volcanic eruptions of the past decade in the Northern Hemisphere. A strong positive signal was detected
by all the existing networks either ground based (Brewer, EARLINET, AirBase) or from satellites (OMI,
GOME-2). The study particularly examines the adequacy of the existing Brewer network to detect SO 2 plumes
of volcanic origin in comparison to other networks and satellite platforms. The comparison with OMI and 45
GOME-2 SO 2 space-borne retrievals shows statistically significant agreement between the Brewer network data
and the collocated satellite overpasses. It is shown that the Brewer instrument is capable of detecting significant columnar SO 2 increases following large volcanic eruptions, when SO 2 levels rise well above the instrumental
noise of daily observations, estimated to be of the order of 2 DU. A model exercise from the MACC project
shows that the large increases of SO 2 over Europe following the Bárðarbunga eruption in Iceland were not
caused by local sources or ship emissions but are clearly linked to the eruption. We propose that by combining
Brewer data with that from other networks and satellites, a useful tool aided by trajectory analyses and modeling
could be created which can be used to forecast high SO 2 values both at ground level and in air flight corridors
following future eruptions
Reduction of blood culture contamination rate by an educational intervention
Background: Although mechanical dyssynchrony parameters derived by speckle tracking echocardiography (STE) may predict response to cardiac resynchronization therapy (CRT), comparability of parameters derived with different STE vendors is unknown. Methods: In the MARC study, echocardiographic images of heart failure patients obtained before CRT implantation were prospectively analysed with vendor specific STE software (GE EchoPac and Philips QLAB) and vendor-independent software (TomTec 2DCPA). Response was defined as change in left ventricular (LV) end-systolic volume between examination before and six-months after CRT implantation. Basic longitudinal strain and mechanical dyssynchrony parameters (septal to lateral wall delay (SL-delay), septal systolic rebound stretch (SRSsept), and systolic stretch index (SSI)) were obtained from either separate septal and lateral walls, or total LV apical four chamber. Septal strain patterns were categorized in three types. The coefficient of variation and intra-class correlation coefficient (ICC) were analysed. Dyssynchrony parameters were associated with CRT response using univariate regression analysis and C-statistics. Results: Two-hundred eleven patients were analysed. GE-cohort (n = 123): age 68 years (interquartile range (IQR): 61-73), 67% male, QRS-duration 177ms (IQR: 160-192), LV ejection fraction: 26 +/- 7%. Philips-cohort (n = 88): age 67 years (IQR: 59-74), 60% male, QRS-duration: 179 ms (IQR: 166-193), LV ejection fraction: 27 +/- 8. LV derived peak strain was comparable in the GE-(GE: -7.3 +/- 3.1%, TomTec: -6.4 +/- 2.8%, ICC: 0.723) and Philips-cohort (Philips: -7.7 +/- 2.7%, TomTec: -7.7 +/- 3.3%, ICC: 0.749). SL-delay showed low ICC values (GE vs. TomTec: 0.078 and Philips vs. TomTec: 0.025). ICC's of SRSsept and SSI were higher but only weak (GE vs. TomTec: SRSsept: 0.470, SSI: 0.467) (Philips vs. QLAB: SRSsept: 0.419, SSI: 0.421). Comparability of septal strain patterns was low (Cohen's kappa, GE vs. TomTec: 0.221 and Philips vs. TomTec: 0.279). Septal strain patterns, SRSsept and SSI were associated with changes in LV end-systolic volume for all vendors. SRSsept and SSI had relative varying C-statistic values (range: 0.530-0.705) and different cut-off values between vendors. Conclusions: Although global longitudinal strain analysis showed fair comparability, assessment of dyssynchrony parameters was vendor specific and not applicable outside the context of the implemented platform. While the standardization taskforce took an important step for global peak strain, further standardization of STE is still warranted
Homogenization of the long-term global ozonesonde records
Póster presentado en: WMO Technical Conference on Meteorological and Environmental Instruments and Methods of Observation celebrada del 10 al 13 de octubre de 2022 en París
Multi-Sensor Reanalysis (MSR) of total ozone, version 2
The ozone multi-sensor reanalysis (MSR) is a multi-decadal ozone column
data record constructed using all available ozone column satellite data
sets, surface Brewer and Dobson observations and a data assimilation
technique with detailed error modelling. The result is a high-resolution
time series of 6-hourly global ozone column fields and forecast error
fields that may be used for ozone trend analyses as well as detailed
case studies
TEMIS UV index and UV dose MSR-2 data products, version 2
The TEMIS UV index and UV dose data are computed from the assimilated
global ozone field at local solar noon, i.e. at the moment the Sun is
highest in the sky, which in case of the UV dose is combined with the
daily variation of the position of the Sun above the horizon
TEMIS UV index and UV dose operational data products, version 2
The TEMIS UV index and UV dose data are computed from the assimilated
global ozone field at local solar noon, i.e. at the moment the Sun is
highest in the sky, which in case of the UV dose is combined with the
daily variation of the position of the Sun above the horizon
Persistence of Holocene ice cap in northeast Svalbard aided by glacio-isostatic rebound
The deglaciation of the Svalbard-Barents Sea Ice Sheet was driven by relative sea-level rise, the incursion of
North Atlantic waters around Spitsbergen, and increasing summer insolation. However, ice retreat was inter rupted by asynchronous re-advances that occurred into high relative seas, during a period associated with warm
regional waters and elevated summer temperatures. Better understanding of this complex style of deglaciation
and the dynamic response to a warming climate can serve as an important analogue for modern warming and
today’s ice sheets. We present evidence from northern Svalbard of glacier re-advances during the Late Glacial Early Holocene in hand with relative sea-level history and the occurrence of thermophilous molluscs. We
argue that glacio-isostatic adjustment during the transition into the Holocene influenced ice marginal dynamics
and as a result, the southern region of the Åsgardfonna ice cap persisted through the Holocene Thermal
Maximum
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